co.elastic.apm.agent.sdk.state.CallDepth Maven / Gradle / Ivy
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* the Apache License, Version 2.0 (the "License"); you may
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* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
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* specific language governing permissions and limitations
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*/
package co.elastic.apm.agent.sdk.state;
import net.bytebuddy.asm.Advice;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
/**
* A utility that makes it easy to detect nested method calls.
*/
public class CallDepth {
private static final ConcurrentMap registry = new ConcurrentHashMap<>();
private final ThreadLocal callDepthPerThread = new ThreadLocal();
private CallDepth() {
}
/**
* Returns or creates a globally shared call depth instance, based on the advice's class name.
*
* @param adviceClass the class of the advice the call depth is used in.
* @return a globally shared call depth instance, based on the advice's class name.
* @see GlobalVariables
*/
public static CallDepth get(Class> adviceClass) {
// we want to return the same CallDepth instance even if the advice class has been loaded from different class loaders
String key = adviceClass.getName();
CallDepth callDepth = registry.get(key);
if (callDepth == null) {
registry.putIfAbsent(key, new CallDepth());
callDepth = registry.get(key);
}
return callDepth;
}
static void clearRegistry() {
registry.clear();
}
/**
* Gets and increments the call depth counter.
* Returns {@code 0} if this is the outer-most (non-nested) invocation.
*
* @return the call depth before it has been incremented
*/
public int increment() {
int depth = get();
set(depth + 1);
return depth;
}
/**
* Calls {@link #increment()} and returns {@code false} if this is the outer-most (non-nested) invocation.
*
* @return {@code false} if this is the outer-most (non-nested) invocation, {@code true} otherwise
*/
public boolean isNestedCallAndIncrement() {
return increment() != 0;
}
/**
* Decrements and gets the call depth counter.
* Returns {@code 0} if this is the outer-most (non-nested) invocation.
*
* Note: this should be the first thing called on exit advices.
* Also make sure to set {@link Advice.OnMethodExit#onThrowable()} to {@link Throwable}{@code .class}.
* This ensures we don't end up with inconsistent counts.
*
*
* @return the call depth after it has been incremented
*/
public int decrement() {
int depth = get() - 1;
set(depth);
assert depth >= 0;
return depth;
}
/**
* Calls {@link #decrement()} and returns {@code false} if this is the outer-most (non-nested) invocation.
*
* Note: this should be the first thing called on exit advices.
* Also make sure to set {@link Advice.OnMethodExit#onThrowable()} to {@link Throwable}{@code .class}.
* This ensures we don't end up with inconsistent counts.
*
*
* @return {@code false} if this is the outer-most (non-nested) invocation, {@code true} otherwise
*/
public boolean isNestedCallAndDecrement() {
return decrement() != 0;
}
private int get() {
Integer callDepthForCurrentThread = callDepthPerThread.get();
if (callDepthForCurrentThread == null) {
callDepthForCurrentThread = 0;
callDepthPerThread.set(callDepthForCurrentThread);
}
return callDepthForCurrentThread;
}
private void set(int depth) {
callDepthPerThread.set(depth);
}
}